This application claims the priority of German Application No. 100 03 861.1 filed Jan. 28, 2000, which is incorporated herein by reference.
This invention relates to an apparatus for detecting whether a cotton or chemical fiber sliver in a fiber processing machine, particularly a draw frame, is advanced or is stationary and/or whether it is present or absent. The sliver passes through a space accommodating at least one sensor device composed of a transmitter and a receiver. The direction of sensor rays (such as light rays) is essentially perpendicular to the advancing direction of the sliver.
In a known device as disclosed in German Offenlegungsschrift (application published without examination) No. 38 34 110, to which corresponds U.S. Pat. No. 4,982,477, the thickness of the sliver is consecutively measured by a sensor device and, by comparing the data with at least one previous measurement, it is determined whether changes in the thickness occur as a function of time. A difference in the thickness measured indicates that the sliver moves. It is a disadvantage of such an arrangement that the sensor device is structurally expensive. In particular, the receiving device for detecting the sliver thickness (shadow effect) is complex.
It is an object of the invention to provide an improved apparatus of the above-outlined type from which the discussed disadvantages are eliminated and which, in particular, is structurally simple and economical.
This object and others to become apparent as the specification progresses, are accomplished by the invention, according to which, briefly stated, a fiber processing machine includes an arrangement for forwarding a sliver through a space in an advancing direction; an arrangement for continuously displacing the sliver in the space transversely to the advancing direction while the sliver is forwarded in the advancing direction; and an apparatus for detecting a presence, absence, motion or standstill of a sliver. The apparatus according to the invention includes a transmitter emitting a sensor beam passing through the space transversely to advancing direction for being intermittently interrupted by the sliver during displacement thereof transversely to the advancing direction; and a receiver positioned in a path of the sensor beam for receiving a light or a dark signal dependent whether or not the sensor beam is interrupted by the sliver during displacement thereof transversely to the advancing direction.
A sliver motion in the advancing direction may be detected in a simple manner by virtue of the fact that the sliver is movable along a path lying in a plane which is essentially perpendicular to the advancing direction. When the sliver periodically intersects (interrupts) the sensor rays, it is an indication that the sliver moves in the advancing direction. When the rays are continuously either interrupted or not interrupted, it is an indication that the sliver is either stationary or no sliver is present (that is, a sliver rupture has occurred). It is a particular advantage of such an arrangement that the transmitter and the receiverxe2x80x94in contrast to the known devicexe2x80x94need not measure the thickness of the sliver; rather, a detection of interruption or non-interruption of the rays suffices, resulting in an overall economical device.
The invention has the following additional advantageous features:
The path of the sliver may be circular or oval.
The space where measurement takes place is the inner space of a sliver guide.
The optical or electro-optical transmitter and receiver elements are integrated in the sliver guide.
The inner space of the sliver guide has a circular outline.
The sliver guide is situated at the creel of a draw frame, between a coiler can and a deflecting roll (supply roll) mounted on the creel.
The transmitter and the receiver are situated in the sliver guide and a transmitter part and a receiver part are flush with the inner wall defining the inner space of the sliver guide.
Between the transmitter and the receiver a ray-deflecting mirror (reflector) is provided.
The transmitter and the receiver are connected to an electronic microcomputer control-and-regulating device (computer) and the signals produced by the receiver are processed by an electronic evaluating device.
The fiber processing machine simultaneously handles a plurality of slivers, each passing through its own sliver guide and with each sliver guide a separate sensor apparatus is associated.
The invention further encompasses an apparatus for detecting textile fibers in fiber processing machines, particularly draw frames, where, one or more electrooptical transmitters, receivers and/or reflector (mirror) combinations are provided for each sliver to be sensed. Each such combination is preferably integrated into a respective sliver guide. The signals of the receivers are centrally processed by an evaluating unit which is connected to the usual machine control system, and, for an optimal detection, obtains information on the condition of the fiber processing machine and transfers information on all the incoming slivers to the machine control system. A substantial economic advantage is obtained by virtue of the fact that for a plurality of detecting units a central evaluating unit is provided which is connected with the usual machine control. In addition, for a better and more secure detection, the evaluating unit may utilize information on the momentary operating parameters of the draw frame such as output speed.
The invention has the following additional advantageous features:
The presence of slivers and/or their displacement during processing is monitored.
The detection system operates in a xe2x80x9cself-learningxe2x80x9d mode in which the signal pattern used for comparison during a learning phase or during certain occurrences is saved. Since the sliver in practice often does not move on an ideal circular path and the shape of the actual displacement depends, among others, from the material used, the output rate as well as the sliver thickness, the material-specific and production-specific behavior of the sliver may be detected once or continuously by self-learning. Thereafter the results may be repeatedly compared with the production in progress and in case of significant deviations, a suitable response (for example, braking) is triggered. Thus, in this manner material-specific and production-specific signal patterns of the receiver may be generated and stored and may be called later if needed for comparison. Such a function is particularly advantageous for a plurality of sensor units when a central evaluating unit is used.
The detected signal patterns are automatically or manually adjusted as a function of production conditions. Given such a possibility, the detected signal pattern may be adjusted, for example, as a function of changes in the production speed and to thus again obtain an operationally reliable detection.
The utilized signal patterns are adjusted or corrected as a function of certain production parameters of the fiber processing machine.
The electrooptical transmitter and receiver elements are not situated in the detection unit but at another location, preferably on the evaluating unit and transfer the optical information by means of optical wave guides from the detection unit to the transmitter and receiver elements. This provides for a further advantageous possibility to economically build the detection units having a small spatial requirement.
The motion of the sliver is detected by comparing the generated signal pattern emitted by the receiver with a previously inputted pattern.
The evaluation of the receiver signals is carried out while taking certain production parameters into consideration.
The fiber processing machine is controlled as a function of the evaluated signals.
The evaluating unit transfers separate signals for xe2x80x9csliver is presentxe2x80x9d and xe2x80x9csliver is in motionxe2x80x9d to the machine control system.
The evaluating unit transfers in each instance a joint signal to the machine control for all the receivers. By virtue of the fact that the evaluating unit delivers a joint signal for all connected detecting units to the machine control, an advantageous embodiment of the evaluating device is obtained.
The braking of the fiber processing machine occurs when a sliver is missing or is stationary, dependent on the position of the sliver. Since such a braking has to occur very rapidly (substantial deceleration), the moving components (for example, drive belts of the machine) are highly stressed. It is therefore desired that such a braking not be more forceful than absolutely necessary to thus only ensure that the remainder of a broken sliver does not enter into the measuring intake trumpet. Thus, since the intake locations of the slivers may be several meters apart, in case of a failure of an incoming sliver which enters the machine at a substantial distance from the measuring intake trumpet, the machine may be braked less forcefully and thus the material is more gently handled than in case of a sliver which enters very close to the trumpet.
Expediently, plausibility checks are being carried out. The evaluating unit, apart from determining xe2x80x9csliver present/not presentxe2x80x9d and xe2x80x9csliver moves/doesn""t movexe2x80x9d, may transmit further information to the engine control system, for example, for the purpose of plausibility checks.